Complex transfer systems are frequently utilized in industries such as the metalworking industry to transfer work pieces through a series of linearly aligned, spaced apart workstations such as are present in a transfer press. At each workstation, an operation such as stamping is performed on the work piece. As the transfer system moves the work piece through the workstations of the press, a sequence of operations is performed upon the work pieces.
Each press includes a ram positioned above a bolster. At each workstation in the press, an upper die half is affixed to the ram and a lower die half is affixed to the bolster. The die halves are aligned so that, as the ram moves downward, the die halves perform a stamping or other operation on the work piece positioned between the die halves.
To move work pieces successively through the workstations, the work pieces must be moved along a first longitudinal axis, a second, vertical axis and a third, horizontal axis, extending laterally to the longitudinal axis. My U.S. Pat. No. 5,105,647 discloses a transfer system in which a transfer rail extending along the first, longitudinal axis and spaced apart from the press, is supported for movement along the second, vertical axis between a raised and lowered position. The transfer rail is also supported for movement along the third, horizontal axis between a forward position proximate to the press and a retracted position. A finger rail is slidably mounted to the transfer rail so that the finger rail is moveable along the first, longitudinal axis. The work pieces are gripped by work piece grippers which are mounted to the finger rail. As the finger rail moves longitudinally with respect to the transfer rail, the work pieces held by the grippers may be positioned at various points along the first, longitudinal axis. As the transfer rail moves along the second, vertical axis and along the third, horizontal axis, the work pieces may be raised or lowered and placed proximate to or retracted from the press.
My patent further discloses a system for transferring work pieces through a series of workstations wherein independently supported actuator units such as a dual axis hydraulic actuator are provided which have a lateral arm to support the transfer rail and to impart up and down and back and forth movement to it. Individually controllable means are provided for imparting reciprocal linear motion to the finger rail along the direction of travel of the work pieces as they pass through the workstations. Means are provided for centrally controlling the movement of the transfer rail and finger operator rail to synchronize travel of the work pieces through the successive workstations in timed relation with performance of the sequence of operations. The central control system coordinates the large number of complicated transfers and multiple realignments.